Hydraulic fracturing is now a commonly used method for creating fractures that extend from a bore hole into the surrounding rock formations. This method may also be informally referred to as “fracing” or “hydrofrac.” Although hydraulic fracturing is perhaps most commonly employed to stimulate production from oil and gas wells, it is also applied in stimulating ground water wells, preconditioning rock for caving or inducing rock to cave in mining, as a means of enhancing waste remedial processes, to dispose of waste by injection into suitable deep rock formations, and as a method to measure the stress in the Earth.
In accordance with hydraulic fracturing processes, multiple fracture tanks are transported to a bore hole site with these fracture tanks storing the fluid that is to be employed in the hydraulic fracturing method. The fluid held in the fracture tanks is injected into the bore hole at a rate and pressure sufficient for creating or restoring fractures in the surrounding formation, thereby increasing the surface area of the formation that is exposed to the bore hole. The fractures provide a path along which fluids or gases may flow either from the formation into the bore hole (in the case of extracting fluids or gases) or from the bore hole into the surrounding formation (in the case of injecting fluid or gas into a formation). With respect to oil recovery, the fractures serve to increase the rate at which oil can flow from the surrounding formation into the bore hole for extraction.
In a given hydraulic fracturing operation, multiple fracture tanks will be required inasmuch as each tank can only hold a limited amount of fracturing fluid. The fracture tanks employed in the art are simply storage trailers that are transported to the site by a tractor truck. That is, the typical fracture tank is a trailer portion of a tractor-trailer combination. When the bore hole is located at a site having flat terrain, it is usually sufficient to simply drive the tractor-trailer combination to the desired location in the area surrounding the bore hole such that the fracture tank can be accessed and used when necessary. However, when the area surrounding the bore hole is hilly or otherwise not sufficiently flat, the tractor may be unable to transport the fracture tank (i.e., trailer) to the desired location. Similarly, if the terrain surrounding the bore hole is moist, the tractor-trailer combination often times becomes stuck. Thus, the fracture tanks can usually only be transported around a bore hole site if that site is flat and well drained, and, in hilly regions or moist/muddy soil, it has been found necessary to transport the fracturing tanks by pushing them with bulldozers.
Notably, fracture tanks of the prior art are not specifically given to being pushed around by bulldozers. Thus, a number of problems are encountered. For example, the undercarriages of the fracture tanks have transverse strengthening ribs or joists, and mud can collect between these ribs such that the fracture tank becomes bogged down and is difficult to maneuver, even with the bulldozer. Additionally, after the fracture tank is removed from the site, mud clumps can fall out from the undercarriage during road transport, and this can be dangerous for other vehicles on the road. Thus, the fracture tanks may need to be cleaned and otherwise maintenanced, increasing the costs in using such tanks.
Because the fracture tanks are not constructed for being manipulated by a bulldozer, the tanks can often become damaged by the bulldozer, again increasing the costs. The fracture tanks can become stuck in the mud in moist terrain, and the bulldozer, which is sufficiently powerful enough to move the fracture tank, can damage portions of the tank by forcing against the resistance of the mud. This is specifically true when a tank has been allowed to sit for some time, permitting the mud to dry around portions of the tank. For example, the rear wheels and spring hangers on which they are mounted can sometimes become encased in dried mud and a bulldozer pushing on the fracture tank can cause the wheels, spring hangers, or even the support beams to which they are mounted to become twisted or otherwise structurally compromised.
Water is one of the most common fracturing fluids employed in hydraulic fracturing, and, when it is employed can sometimes be drawn from local lakes and streams and the like. Thus, it is not uncommon for the fracture tanks hold not only water but algae, water plants and other debris. This debris tends to clog the outlet port of the fracture tank and must therefore be periodically removed. In the prior art, the fracture tanks have simply been cleaned by workers entering the tanks and physically removing the algae, plant matter, debris, etc.
In cold climates, the fluid held in a fracture tank may freeze, and this may result in damage to the fracture tank and/or render the tank useless for operation.
Further, because moving items by bulldozer is not a precise way to position items, it is common for one fracture tank to be pushed forcefully into another in an attempt to align the multiple fracture tanks at a desired location near the bore hole. Additionally, it is often necessary for workers to climb atop a fracture tank and safely walk from one to another, in areas where mud, rain and snow may make such walking dangerous.
Thus, there is a need in the art for a fracture tank that is easy to. manipulate in hilly and muddy terrain, that has ready means for heating, cleaning and flushing, that is easily ganged with other fracture tanks, and that is safe to walk upon, and from one to another.